Safety device for engines



Oct. 12, 1937. J. sANTscHl 2,095,349 l SAFETY DEVICE` FOR ENGINES Filed Oct. 25, 19,34

INTERSTAGE COOLER oF MULTI STAGE Am COMPRESSOR,

nventor lttomegs the pump wasV inoperative; As the fuel pump Fig. 3 is a view similar to a portion of Fig. 1 l0 lysomederangement ofthe control mechanism. sion spring II which encircles the rod I2 cone leased bythe safety stop may` also fail to shift Spring Il is of such strength that at a critical 25 Y maybeused, itbeing practicable to provide a supply pressure and by coil compression spring 4Patented 0t.129,1937Y Y. Y i Y 2,095,349

QUNITED STATES PATENT orties SAFETY DEVICE Foa ENGINESV Jean Santschi, Milwaukee, Wis., assigner to Nordberg Manufacturing Company, Milwaukee, Wis., a corporation of Wisconsin Application October 25, 1934, Serial No. 750,614

7 Claims. (Cl. 12S-140) y yThisV invention relates to safety stop mechatypes of fuel pump will now be described with nisms, and particularly to safety stops for Diesel reference to the accompanying drawin in and other internal combustion engines inwhich which,- fuel is supplied tothe cylinders by pumps. Fig. 1 is a diagrammatic elevation of the safety It has been the usual practice to provide a destop trip pneumatically connected with a six vice-driven by the engine and arranged to funcplunger fuel oil pump for a six cylinder air intion at a critical excess speed to trip avlatch. The jection Diesel engine. Parts arebroken away to tripping of the latch permitted a weight to shift show the construction.

the fuel pump controller to a position in which Fig. 2 is an axial section through the air valve.

and latch mechanism were usually located far andillustrating the invention applied to fuel feed-r apart, this required long and inconvenient meing pump of another type. Y chanical connections between thelatch and the Referring first to Figs. 1 and 2, 6 represents fuel pump controller. #These connections -Were the rotary element of the safety stop, here shown in the way, unsightly andsubject to Vderangeas a wheel. It is mounted on a shaft l which l5 ment. i z *y l l Y Vmay be the crank shaft or the cam shaft of the Another objection tothe prior art arrangeengine, or any shaft driven thereby. Pivoted at ment is .thefactv thatit -acts through the same 8 on wheel 6 is Yan arm 9 urged outward by cencontrol mechanism as .does the ordinary governor. trifugal force and held in throughout the nor- `When an engine runs away, the cause is commonmal speed range of the engine by acoil comprese EozgrvexampleQ-ifiithe, control mechanism is stuck nected with arm 9. so that the governor doesk not properly shift it, The arm 9 has a finger I3, which may be prothere isfserious risk1that the weightgwhen rejected through an opening in the rim of wheel 6.

it.. ,In such case the safety stop would fail to speed, slightly above normal engine speed, the function because of the very condition that caused spring is overpowered by the centrifugal force .de- ,theeng'ineto runaway.. I l veloped byl arm 9. The arm 9 then swings out- The present invention provides a simple deward and finger I3 projects beyond the rim of `vice in` whichrthe tripping of the latch opens'a wheel 6 far enough to strike trigger I4'of a latch 30 valve.: j The opening of the valve admits air under mechanism in housing I5. The shifting of trigmoderate pressureV (usually 5 to 10 pounds gage) ger I4 releases -arm I6 which is then drawn down .tothe intake manifold of the fuel pump. The reby spring I'I. Y i

sulting` immediate displacement of fuel oil from The mechanism so far described will be recogsuchmanifold puts the fuel pump out of action nized as the trip mechanism of a well-known `and stops the engine. In this device a simple safety stop. In that device, as heretofore con-V pipe leading from the air valve to a connection alstructed, arm I6 is connected by a cable with the readypresentrin commercial oil pumps, takes the Vcontrol member of the fuel pump, but according placeofall mechanical connections,fand the fuel to the present invention the descent of arm I6 is pump controller is freed from the special weightcaused to open anair valve. `actuated .connections heretofore used. The con- The Ybody of the air valve is indicated at I8. troller takes noV part in the stopping operation To this' a supply line I9 leads from any suitable and if fstuckcannot defeat theA stopping of the source of air preferably under pressure of 5 to engine.l g f Y 10 pounds gage.V In Fig. 1 it is shown connected Inan air injection Diesel engine the necessary to the air passage of the rst interstage cooler air can conveniently be derived from the first 2Il of the multistage compressor which supplies` vstage of the compressor. which furnishes injectfuel injecting air. From body I8 a line 2| leads ing air. `When air startingV is used air may loeY to the supply manifold of the fuel pumphereinvtaken at reduced pressure from the starting after described.

bottle. LScavenging airV is" seldom at sufficient In bodyY I'8 (see Fig. 2) is a seat for the down'- 50 pressure. Any source offering adequate, pressure wardly opening check valve 22 urged closed by Y .small compressor and accumulator specially forV 23 which is interposed between the valve and a this. DUIIlSIOSc.i` combined spring seat and closure 'plug 24 thread- 4'Ipwcvafillns rativefembodiments, using differentV Y edinto body I8. "A plunger 25 guided'in a plug 55 25, also threaded into body I8, engages the upper end of valve 22 and projects above plug 26 into the path of lever i6.

The descent of lever I6 when released by the actuation of trigger l5, opens valve 22 and allows air to ovv from supply line i9 to line 2 i.

A multiple unit fuel pump of the type manufactured by the inventors assignee is indicated generally by the numeral 3|. The drive shaft 32 of the pump is driven by the engine Which it serves, and carries cams (not shown) which reciprocate in suitably timed relation, a series of pump plungers 33, one for each engine cylinder. Four such plungers are visible, and each works in a corresponding pump cylinder 34.

In front of each pump cylinder is a related valve cage 35, one of which appears in section in v Fig. 1. In each cage 35 is a discharge check valve 36 through which displaced oil flows to a connection 3l' and thence to the injection valve of the correspo-nding engine cylinder. Above each discharge valve is an inlet valve 38 also of the check type through which oil flows from the manifold 39 to the pump cylinder. Valves 38 are urged closed by compression springs 4l and are held open through variable portions of the discharge strokes of respective plungers 33 by push rods 42 which are depressed by rockers 43. The mechanism which actuates rockers 43 is conn trolled by the engine governor (not shown), and by varying the portion of the pump stroke through which the inlet valve is held open, varies the quantity of oil fed per stroke to the en gine cylinders.

The pump 3l is a multiple unit pump of the variable spill-back type extensively used in the art, and no novelty is here claimed for it. Hence it need not be described in great detail.

The fuel supply manifold 39 receives fuel oil through screen 44 from a short stand pipe 45. Oil is supplied to stand pipe 45 through pipe 46 at a rate slightly in excess of the maximum demand. The excess flows over the dam 4l and returns by pipe 48 to the supply. The valve 49 is provided to drain the manifold and normally is closed.

The pipe 2| leading from the air valve is carried in an inverted U 5l above the top of stand pipe 45 and then down to connection 52 which leads to the interior of manifold 39. The inverted U 5| is to keep pipe 2l free of oil.

The opening of valve 22 by the safety stop admits air to manifold 39, The air displaces the oil from the manifold and stops the engine by terminating the fuel feed. They displaced oil merely flows over` the dam 4I back to supply. Even if the oil be not completely displaced, the entry of air into the pumps puts them out of action.

In Fig. 3 the invention is shown applied to another type of fuel pump, namely that manufactured by Robert Bosch. Parts essentially the same as those shown in Fig. l have the same reference numeral with the character a.

A single pump, for a single engine cylinder is illustrated. The pump body is illustrated at 6|. Guided in this is an actuating cross head 62 urged downward by spring 63'and intended to be forced upward by a part of the engine which reciprocates in proper timed relation to the rotation of the crank shaft.

The pump cylinder 64 is mounted in body 6l and has at its upper end the discharge valve 35 With spring 66. Valve 65 is of the check type and prevents reflux from the discharge connection 6l which is connected to the fuel injecting device of the engine.

The supply connection 68 for fuel oil is fed from stand pipe 45a and from it an inlet port 69 leads through the side of cylinder 64. 'Ihis port is controlled by the end 'I2 of pump plunger 'H Which is specially formed to serve as a spill back valve, the amount of spill back being varied by turning the plunger about its longitudinal axis.

To permit this adjustment plunger 'H is swiveled on crosshead 62 at l'3 and is splined at 14 to sleeve 15. A gear 16 integral With sleeve 15 meshes with a rack 'l1 which is guided in pump body 6|.

The engine governor (not shown) controls the position of rack 'Il and thus by regulating the spill back, regulates the quantity of oil fed by the pump at each stroke.

A check valve 18 is indicated in line 2la and closes against flow from the supply connection 68 toward valve Illa. This performs the same function as loop 5I, that is, it prevents fuel oil from flowing to valve i 8a. Either arrangement may be used but the loop 5I is considered to be simpler and probably more certain in action.

The structure of Fig. 3 operates in the same manner as that shown in Fig. l, so far as stopping by displacing oil from the pump supply connection is concerned.

While the use of compressed air has been described, and is preferred because air is readily available, other suitable gases if available under pressure can be used.

The trip mechanism illustrated isfconventional and is intended to be typical. of the air valve. The invention may be applied to any fuel pump Whose construction and supply connections permit the displacement of fuel voil by a compressed gas.

What is claimed is,-

l. The combination of a fuel pump for supplying measured charges of liquid fuel to the Working space of an internal combustion engine, said fuel pump including a supply passage; a normally closed valve for admitting a gas under pres- 5 sure to said supply passage, said gas when admitted serving to displace fuel from said passage, said gas being incapable of serving as amotive fuel for the engine; and means responsive to engine speed and arranged to open said valve at a critical speed in excess of the normal speed of the engine.

2. The combination of a fuel pump for feeding measured charges of fuel oil to the Working space of an .internal combustion engine, said pump including a. fuel supply passage; means including a standpipe provided with an overflow, said standpipe serving to supply fuel to said passage under moderate pressure head; a normally closed valve for supplying gas under pressure to said passage to displace fuel therefrom against said pressure head, said gas being incapable of serving as a motive fuel for the engine; and means responsive to engine speed and arranged to open said valve at a critical speed in excess of the normal speed of the engine.

3. The combination of a pump arranged to supply measured charges of liquid fuel to the Working space of an internal combustion engine,

said pump including a supply passage; means for controlling said pump to vary the measured charge delivered thereby; a normally closed valve controlling a supply of gas under pressure to said supply passage, said gas when admitted'to the passage displacing fuel therefrom, said gas being The same is true I incapable of serving as a motive fuel for the engine; and means responsive to engine speed and arranged toA open said valve when engine Vspeed exceeds a chosen critical value.

4. The combination of a fuel pump for supplying measured charges of liquid fuel to the working space of an internal combustion engine, said fuel pump including an inlet valve and a supply passage leading thereto; means for normally supplying liquid fuelto said supply passage; and means responsive to abnormal operation of the engine for terminating the supply of fuel to said supply passage by the displacing action of a gas,

said gas being incapable of serving as a motive Y fuel for the engine.

5. 'The combination of a plurality of fuel pumps for supplying measured charges of fuel to the various Working spaces of a multiple cylinder internal combustion engine, said fuel pumps having a common supply passage for liquid fuel; a normally closed valve for admitting a gas under pressure to said supply passage, said gas when admitted serving to displace fuel from said passage and being incapable of serving' as a motive fuel for the engine; and means responsive to engine speed and arranged to open said valve at a critical speed in excess of the normal speed of the engine. j

6. The combination of a plurality of fuel pumps for feeding measured charges of fuel oil to the various working spaces of a multiple cylinder combustion engine, said pumps including a supply passage common to all the pumps for supplying fuel oil thereto; means including a standpipe;

provided with an overow, said standpipe serving to supply fuel to said passage under moderate pressure head; a normally closed valve for supplying gas under pressure to said passage to displace fuel oil therefrom against said pressure head, said gas being incapable of serving as a motive fuel for said engine; and means responsive to engine speed and arranged to open said valve at critical speed in excess of the normal speed of the engine.

7. The combination of a fuel pump for supplying measured charges of liquid fuel to the working space of an internal combustion engine, said fuel pump including a supply passage; and normally inactive means arranged to be rendered active by abnormal operation of the engine to admit gas under pressure to said supply passage, said gas being incapable of serving'as a motive fuel for said engine, and the admission of said gas to the supply passage serving to completely suspend the fuel pumping operation of the pump.

JEAN SANTSCHI. 

